1. Field of the Invention.
The present invention relates to video teleconferencing systems, and more particularly to a video teleconferencing apparatus that enables direct eye contact between participants in a teleconference and that may be retracted to enable ordinary use of the monitor when a video teleconference is not in session.
2. Description of the Related Art.
Video teleconferencing systems enable two or more parties to participate in remote conversation with accompanying near real-time video. As shown in FIG. 1, in a conventional video teleconferencing system, each party communicates by means of a teleconferencing station 100. For processing the video portion of the conversation, each teleconferencing station includes a display device 102, i.e., a monitor or CRT, for displaying the other party/parties to the conversation, and a video camera 104 for transmitting video to the other parties to the conversation. The video camera 104 is mounted adjacent to the display 102, just above or to the side of the display screen.
A problem with such systems is that the optical paths 106 and 108 for the display device 102 and the video camera 104 are divergent. As a result, a participant in a teleconferencing session appears to be talking to the other session participants without eye contact. This reduces the impact, interest and sincerity of the message being communicated by the speaker, and may even be interpreted as a lack of honesty.
In order to overcome this problem, several devices have been developed. Tanigaki, U.S. Pat. No. 4,400,725, relates to a video display device and video pickup device which are arranged on a common optical axis. In this device, the video display is placed in front of the video camera and comprises display elements made of a trans-illumination controllable material. The camera is mounted on a common optical axis of the display device, and may be mounted inside of or behind the display. This type of device is very expensive to manufacture and is not suitable to retrofit an existing monitor.
Martinez et al., U.S. Pat. No. 5,168,354, relates to a drive-thru restaurant system in which the patron may maintain eye-to-eye contact with an attendant in the restaurant. The system includes an attendant station in the restaurant having a video monitor positioned to project the image of the customer to the attendant. The attendant station also includes a video camera mounted at eye-level which picks up the eye-level video image of the attendant and transmits this image to a second video monitor located at the remote order station. A mirror, such as reflective one-way glass, mounted within the attendant station allows the attendant to view the video monitor while simultaneously looking directly at the video camera.
This device suffers from several shortcomings. First, it is relatively large and bulky, and therefore not suitable for use in an office or home environment. Second, the video monitor is mounted above the video camera facing downward, which is not a desirable configuration. Finally, the device is not suitable for retrofitting an existing monitor to create a teleconferencing system.
In another type of teleconferencing apparatus sold by Tekskil.TM. Industries, Inc. under the tradename "EyeLine", as shown in FIG. 2, a frame 206 is mounted to a conventional video monitor 214. Mounted within the frame 206 and covering the face of the display is a beamsplitter 208 which is mounted at a 45.degree. angle relative to the display. A secondary mirror 210 also mounted within the frame reflects the image reflected by the beamsplitter 208 onto a conventional video camera 212. Beamsplitter 208 transmits 50% of the light which is directed toward it, and reflects the remaining 50%. Thus, a person utilizing the system may look directly at the monitor, and see the video display of the other party to the conversation while maintaining eye contact.
While this device is capable of being retrofitted to an existing video monitor, it is relatively complicated to do so. In addition to mounting the frame to the monitor, it is necessary to also mount the video camera to the monitor in a separate step. Since these elements are mounted separately, it is necessary to properly align them when setting up the system. The optics are also subject to being knocked out of alignment during normal use of the device.
FIG. 3 shows a further teleconferencing apparatus in which an optical assembly is mounted to a video monitor having an optical axis "C". A housing 302 is secured to the video monitor 304 adjacent to the display. A beamsplitter 306 is mounted within the housing crossing the optical axis so that optical images directed toward the display along the optical axis are partially reflected by the beamsplitter. A video camera 308 is mounted within the housing positioned relative to the beamsplitter for receiving the partially reflected images and for generating a video signal corresponding to the partially reflected images. The beamsplitter is mounted at a 45.degree. angle relative to the optical axis. Since the relationship between the beamsplitter and the camera is fixed, no optical adjustment is required. The housing is secured to the monitor in a manner so that it may be retrofitted to an existing video monitor.
The housing of this device must be attached to the monitor in proper alignment each time the device is to be used, which is inconvenient. Once removed, the housing requires storage space. Also, each time the device is attached to and removed from the display, there is a risk of damage to the device and electrical cable associated with the camera. Accordingly, it would be desirable to have a video teleconferencing apparatus that is capable of retrofitting an existing monitor and which does not have to be removed from the monitor to make full normal use of the monitor.